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FreeBSD-SA-09:01.lukemftpd                                  Security Advisory
                                                          The FreeBSD Project

Topic:          Cross-site request forgery in lukemftpd(8)

Category:       core
Module:         lukemftpd
Announced:      2009-01-07
Credits:        Maksymilian Arciemowicz
Affects:        All supported versions of FreeBSD.
Corrected:      2009-01-07 20:17:55 UTC (RELENG_7, 7.1-STABLE)
                2009-01-07 20:17:55 UTC (RELENG_7_1, 7.1-RELEASE-p1)
                2009-01-07 20:17:55 UTC (RELENG_7_0, 7.0-RELEASE-p8)
                2009-01-07 20:17:55 UTC (RELENG_6, 6.4-STABLE)
                2009-01-07 20:17:55 UTC (RELENG_6_4, 6.4-RELEASE-p2)
                2009-01-07 20:17:55 UTC (RELENG_6_3, 6.3-RELEASE-p8)
CVE Name:       CVE-2008-4247

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

I.   Background

lukemftpd(8) is a general-purpose implementation of File Transfer Protocol
(FTP) server that is shipped with the FreeBSD base system.  It is not enabled
in default installations but can be enabled as either an inetd(8) server,
or a standard-alone server.

A cross-site request forgery attack is a type of malicious exploit that is
mainly targeted to a web browser, by tricking a user trusted by the site
into visiting a specially crafted URL, which in turn executes a command
which performs some privileged operations on behalf of the trusted user
on the victim site.

II.  Problem Description

The lukemftpd(8) server splits long commands into several requests.  This
may result in the server executing a command which is hidden inside
another very long command.

III. Impact

This could, with a specifically crafted command, be used in a
cross-site request forgery attack.

FreeBSD systems running lukemftpd(8) server could act as a point of privilege
escalation in an attack against users using web browser to access trusted
FTP sites.

IV.  Workaround

No workaround is available, but systems not running FTP servers are
not vulnerable.  Systems not running the FreeBSD lukemftpd(8) server are not
affected, but users of other ftp daemons are advised to take care since
several other ftp daemons are known to have related bugs.

NOTE WELL: lukemftpd(8) is a different implementation of an FTP server
than ftpd(8).

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the
RELENG_7_1, RELENG_7_0, RELENG_6_4, or RELENG_6_3 security branch
dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 6.3, 6.4,
7.0, and 7.1 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch http://security.FreeBSD.org/patches/SA-09:01/lukemftpd.patch
# fetch http://security.FreeBSD.org/patches/SA-09:01/lukemftpd.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/libexec/lukemftpd
# make obj && make depend && make && make install

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

CVS:

Branch                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_6
  src/contrib/lukemftpd/src/ftpcmd.y                          1.1.1.5.2.2
  src/contrib/lukemftpd/src/extern.h                          1.1.1.4.2.2
  src/contrib/lukemftpd/src/ftpd.c                                1.4.2.2
RELENG_6_4
  src/UPDATING                                             1.416.2.40.2.5
  src/sys/conf/newvers.sh                                   1.69.2.18.2.8
  src/contrib/lukemftpd/src/ftpcmd.y                      1.1.1.5.2.1.6.1
  src/contrib/lukemftpd/src/extern.h                      1.1.1.4.2.1.6.1
  src/contrib/lukemftpd/src/ftpd.c                            1.4.2.1.6.2
RELENG_6_3
  src/UPDATING                                            1.416.2.37.2.13
  src/sys/conf/newvers.sh                                  1.69.2.15.2.12
  src/contrib/lukemftpd/src/ftpcmd.y                      1.1.1.5.2.1.4.1
  src/contrib/lukemftpd/src/extern.h                      1.1.1.4.2.1.4.1
  src/contrib/lukemftpd/src/ftpd.c                            1.4.2.1.4.1
RELENG_7
  src/contrib/lukemftpd/src/ftpcmd.y                          1.1.1.6.2.1
  src/contrib/lukemftpd/src/extern.h                          1.1.1.5.2.1
  src/contrib/lukemftpd/src/ftpd.c                                1.5.2.1
RELENG_7_1
  src/UPDATING                                             1.507.2.13.2.4
  src/sys/conf/newvers.sh                                    1.72.2.9.2.5
  src/contrib/lukemftpd/src/ftpcmd.y                          1.1.1.6.6.1
  src/contrib/lukemftpd/src/extern.h                          1.1.1.5.6.1
  src/contrib/lukemftpd/src/ftpd.c                                1.5.6.2
RELENG_7_0
  src/UPDATING                                             1.507.2.3.2.12
  src/sys/conf/newvers.sh                                   1.72.2.5.2.12
  src/contrib/lukemftpd/src/ftpcmd.y                          1.1.1.6.4.1
  src/contrib/lukemftpd/src/extern.h                          1.1.1.5.4.1
  src/contrib/lukemftpd/src/ftpd.c                                1.5.4.1
- -------------------------------------------------------------------------

Subversion:

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/6/                                                         r186872
releng/6.4/                                                       r186872
releng/6.3/                                                       r186872
stable/7/                                                         r186872
releng/7.1/                                                       r186872
releng/7.0/                                                       r186872
- -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-4247
http://security.freebsd.org/advisories/FreeBSD-SA-08:12.ftpd.asc

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-09:01.lukemftpd.asc
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